#!/usr/bin/env python
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import numpy as np


def _upcast_float16_array(x):
    """
    Used in _scipy_fftpack to upcast float16 to float32,
    instead of float64, as mkl_fft would do
    """
    if hasattr(x, "dtype"):
        xdt = x.dtype
        if xdt == np.half:
            # no half-precision routines, so convert to single precision
            return np.asarray(x, dtype=np.float32)
        if xdt == np.longdouble and not xdt == np.float64:
            raise ValueError("type %s is not supported" % xdt)
    if not isinstance(x, np.ndarray):
        _x = np.asarray(x)
        xdt = _x.dtype
        if xdt == np.half:
            # no half-precision routines, so convert to single precision
            return np.asarray(_x, dtype=np.float32)
        if xdt == np.longdouble and not xdt == np.float64:
            raise ValueError("type %s is not supported" % xdt)
        return _x
    return x


def _downcast_float128_array(x):
    """
    Used in _numpy_fft to unsafely downcast float128/complex256 to
    complex128, instead of raising an error
    """
    if hasattr(x, "dtype"):
        xdt = x.dtype
        if xdt == np.longdouble and not xdt == np.float64:
            return np.asarray(x, dtype=np.float64)
        elif xdt == np.clongdouble and not xdt == np.complex128:
            return np.asarray(x, dtype=np.complex128)
    if not isinstance(x, np.ndarray):
        _x = np.asarray(x)
        xdt = _x.dtype
        if xdt == np.longdouble and not xdt == np.float64:
            return np.asarray(x, dtype=np.float64)
        elif xdt == np.clongdouble and not xdt == np.complex128:
            return np.asarray(x, dtype=np.complex128)
        return _x
    return x


def _supported_array_or_not_implemented(x):
    """
    Used in _scipy_fft to convert array to float32, float64, complex64,
    or complex128 type or raise NotImplementedError
    """
    _x = np.asarray(x)
    black_list = [np.half]
    if hasattr(np, "float128"):
        black_list.append(np.float128)
    if hasattr(np, "complex256"):
        black_list.append(np.complex256)
    if _x.dtype in black_list:
        raise NotImplementedError
    return _x
